Petrophysical measurements across a uranium roll feature: Rajah-49 Mines, Gateway, Colorado
Explore the source record for details and available documents.
Open-File Report↗
Geology topics
Robert A. Brooks
Publications and source records attributed to Robert A. Brooks.
Carborne radiometric survey of the Nome area, Seward Peninsula, Alaska
A carborne radiometric survey was made along the accessible roads in the Nome, Alaska, area. The background radiation was generally found to be low, about 40 cps, but higher radioactivity near granite was noted. No radioactive anomalies of a magnitude greater than three times the average background were encountered.
Alaska↗
Preliminary investigation of the elemental variation and diagenesis of a tabular uranium deposit, La Sal Mine, San Juan County, Utah
Ore in the La Sal mine, San Juan County, Utah, occurs as a typical tabular-type uranium deposit of the-Colorado Plateau. Uranium-vanadium occurs in the Salt Wash Member of the Jurassic Morrison Formation. Chemical and petrographic analyses were used to determine elemental variation and diagenetic aspects across the orebody. Vanadium is concentrated in the dark clay matrix, which constitutes visible ore. Uranium content is greater above the vanadium zone. Calcium, carbonate carbon, and lead show greater than fifty-fold increase across the ore zone, whereas copper and organic carbon show only a several-fold increase. Large molybdenum concentrations are present in and above the tabular layer, and large selenium concentrations occur below the uranium zone within the richest vanadium zone. Iron is enriched in the vanadium horizon. Chromium is depleted from above the ore and strongly enriched below. Elements that vary directly with the vanadium content include magnesium, iron, selenium, zirconium, strontium, titanium, lead, boron, yttrium, and scandium. The diagenetic sequence is as follows: (1) formation of secondary quartz overgrowths as cement; (2) infilling and lining of remaining pores with amber opaline material; (3) formation of vanadium-rich clay matrix, which has replaced overgrowths as well as quartz grains; (4) replacement of overgrowths and detrital grains by calcite; (5) infilling of pores with barite and the introduction of pyrite and marcasite.
Open-File Report↗
Preliminary report on uranium-, thorium-, and rare-earth-bearing rocks near Golovin, Alaska
Uranium-, thorium-, and rare-earth bearing rocks were found by a U.S. Geological Survey field party 15 miles northeast of Golovin, Alaska, in the southeastern Seward Peninsula (fig. 1) in June 1976. The mineralized areas occur in syenite and appear to be concentrated along the margins of alkaline dikes, with allanite tentatively identified as the principal mineral containing the uranium-, thorium-, and rare-earths. Samples contain as much as 0.15 percent U 3 0 8 and 1.05 percent Th0 2 , and over 2 percent rare-earth elements. These mineralized rocks are closely associated with alkaline dikes which are part of a dike swarm that crops out over at least 250 km 2 (100 mi 2 ). This large dike swarm is thus of considerable economic interest. These uranium-, thorium-, and rare-earth-rich rocks occur near the west end of the western Alaska uranium-thorium province (West, 1953; Clark and others, 1975; Miller, 3976) and were found during a regional investigation of this province by the Geological Survey. The alkaline dikes were known from previous mapping by the two senior authors (Miller and others, 1972) to be anomalously radioactive. The mineralized areas described in this report were found while making a brief study of (1) alteration and/or mineralization associated with these dikes and (2) their relation to similar dikes and rocks which occur elsewhere in the province (Miller, 1972).
Alaska↗